The Japanese government on Tuesday raised the rating of the crisis at the Fukushima Dai-ichi power plant to a level 7. That's the highest possible level on the international scale used to evaluate the seriousness of nuclear incidents.

Nuclear engineers in Japan are dealing with two problems at the same time: They are working to fully stabilize the reactors at the Fukushima Dai-ichi plant, and they are trying to control the release of radioactive material.It could take weeks or months to stabilize the reactors.

Japan was rocked Thursday by a 7.1 magnitude earthquake just off its coast. Technically, that strong shaking was an aftershock of the devastating 9.0 temblor that hit the nation nearly a month ago. But it wasn't a shocker, says Volkan Sevilgen, an earthquake researcher with the U.S.

The earthquake that struck Japan on March 11 will be remembered primarily for the devastating tsunami it created. The quake itself did remarkably little damage to buildings in most areas, thanks to strict construction codes.

More than three weeks after an earthquake and tsunami set off one of the world's most serious nuclear accidents at Japan's Fukushima Dai-ichi plant, experts are intensifying their scrutiny of how the plant operator, Tokyo Electric Power Co., has handled the crisis.Some events TEPCO couldn't hav